The present invention relates to an apparatus for reading and/or writing data markings of an optical recording medium having data markings arranged along a track and header markings arranged laterally offset with respect to the center of this track. The apparatus has a signal conditioner, a header identification unit and a switch unit driven by the latter. The object of the invention is to enable data and header markings to be read out with the lowest possible error rate. For this purpose, the apparatus according to the invention has a threshold value forming unit and a storage unit with at least two storage locations, in which case, by means of the switching unit, the input of the storage unit can be connected to the output of the threshold value forming unit and the output of the said storage unit can be connected to a threshold value input of the signal conditioner. The apparatus according to the invention is suitable for reading from or writing to optical recording media such as a DVD-RAM, for example.
Legal claims defining the scope of protection, as filed with the USPTO.
1. Apparatus for reading or writing data markings ( 25 ) of an optical recording medium ( 1 ) having data markings ( 25 ) arranged along a track ( 20 ) and header markings ( 25 ) arranged laterally offset with respect to the centre of this track ( 20 ), the apparatus comprising a signal conditioner ( 4 ), for generating a conditioned signal out of a signal read from the recording medium a header identification unit ( 9 ) for identifying a header area a switch unit ( 6 ) driven by said header identification unit, a threshold value forming unit ( 5 ) and a storage unit ( 7 ) with at least two storage locations (M 01 , M 02 , M 11 , M 12 , M 21 , M 22 ), wherein, by means of the switch unit ( 6 ), the input of the storage unit ( 7 ) can be connected to the output of the threshold value forming unit ( 5 ) and the output of the said storage unit can be connected to a threshold value input of the signal conditioner ( 4 ).
2. Apparatus according to claim 1 , characterized in that the switch unit ( 6 ) has three switch positions.
3. Apparatus according to claim 1 , characterized in that the threshold value forming unit ( 5 ) and the storage unit ( 7 ) are realized on a digital basis.
4. Apparatus according to claim 1 , characterized in that in each case two storage locations (Mn 1 , Mn 2 ) are provided for each switch position (n 0, 1, 2).
5. Apparatus according to claim 3 , characterized in that in each case two storage locations (Mn 1 , Mn 2 ) are provided for each switch position (n 0, 1, 2).
6. Apparatus according to claim 4 , characterized in that a switch ( 8 ) is present for connecting the threshold value input of the signal conditioner ( 4 ) to the output of the switch unit ( 6 ) or to the output of the threshold value forming unit ( 5 ).
7. Apparatus according to claim 5 , characterized in that a switch ( 8 ) is present for connecting the threshold value input of the signal conditioner ( 4 ) to the output of the switch unit ( 6 ) or to the output of the threshold value forming unit ( 5 ).
8. Method for the error-free read-out of data markings ( 25 ) and header markings ( 25 ) of an optical recording medium ( 1 ) having data markings ( 25 ) arranged along a track ( 20 ) and header markings ( 25 ) arranged laterally offset with respect to the centre of this track ( 20 ), the method comprising the steps forming a threshold value (S) forming a conditioned signal (FS) from a detector signal (HF) by means of said threshold value (S), storing a present threshold value (S 1 ) in a first store (M 01 ) during the reading of a data area ( 24 ) storing the present threshold value (S 1 ) in a second store (M 11 , M 21 ) during the reading of a header area ( 27 , 27 , 27 ), and preventing said storing and instead using the stored threshold value (S 1 ) corresponding to the area ( 24 , 27 , 27 , 27 ) to be newly read for the purpose of forming the conditioned signal (FS), given the presence of a transition from one area of the areas ( 24 , 27 , 27 , 27 ) to another area of the areas ( 24 , 27 , 27 , 27 ).
9. Method according to claim 8 , characterized in that the prevention of new storage and the use of the value already stored are maintained for a predetermined period of time after the identification of a transition.
10. Method according to claim 8 , characterized in that the prevention of new storage and the use of the value already stored are also effected when a defect occurs.
11. Method according to claim 8 , characterized in that in the event of a plurality of different types of header areas ( 27 , 27 , 27 ) or data areas ( 24 ) being present, further stores are provided in which storage is correspondingly effected and from which reading is correspondingly effected.
12. Method according to claim 8 , characterized in that each store has at least two storage locations (Mn 1 , Mn 2 ), in which case storage is effected in a first storage location (Mn 1 ), reading is effected from a second storage location (Mn 2 ), in a manner staggered over time the content of the first storage location (Mn 1 ) is transferred to the second storage location (Mn 2 ) and, in order to interrupt the storage, the transfer from the first storage location (Mn 1 ) to the second storage location (Mn 2 ) is prevented.
13. Method according to claim 11 , characterized in that each store has at least two storage locations (Mn 1 , Mn 2 ), in which case storage is effected in a first storage location (Mn 1 ), reading is effected from a second storage location (Mn 2 ), in a manner staggered over time the content of the first storage location (Mn 1 ) is transferred to the second storage location (Mn 2 ) and, in order to interrupt the storage, the transfer from the first storage location (Mn 1 ) to the second storage location (Mn 2 ) is prevented.
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December 14, 1999
May 28, 2002
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